In May 2013, with a US$3.8 million allocation from CERF, the United Nations Humanitarian Air Service (UNHAS) deployed two Mi8 helicopters to Jonglei State, one of the deadliest areas in South Sudan. CERF/IRIN/Mackenzie Knowles-Coursin

The situation in Jonglei State had deteriorated rapidly after hostilities between the South Sudan army and non-state armed actors flared up in March 2013. Tens of thousands of civilians were displaced by the violence. CERF/IRIN/Mackenzie Knowles-Coursin

The air service has become a critical component of the relief operation where thousands of people remain in hard-to-reach locations which are inaccessible by road, or too insecure to reach by ground travel. During the rainy season, up to 60 per cent of the country is inaccessible by road. CERF/IRIN/Adriane Ohanesian

As well as providing transport for aid workers and emergency relief items such as food, medicine and shelter materials, the service is also crucial for medical and security evacuations. CERF/IRIN/Adriane Ohanesian

Here, the UNHAS helicopter is loaded with soap, tarpaulins, and kitchen sets to be distributed in Kongor, Jonglei State. CERF/IRIN/Mackenzie Knowles-Coursin

More than 5,600 people have been registered for assistance at the distribution centre in Kongor. CERF/IRIN/Mackenzie Knowles-Coursin

Distribution continues as the UNHAS helicopters lifts off and heads back to Bor, the capital of Jonglei State to load up for its next mission. CERF/IRIN/Adriane Ohanesian